WO2019131597A1

WO2019131597A1 - Acrylic block copolymer and anti-fogging film containing same

Info

Publication number: WO2019131597A1
Application number: PCT/JP2018/047493
Authority: WO
Inventors: 健太郎西井
Original assignee: 株式会社ネオス
Priority date: 2017-12-27
Filing date: 2018-12-25
Publication date: 2019-07-04
Also published as: JPWO2019131597A1; JP7239490B2

Abstract

[Problem] To provide: an anti-fogging film capable of sustainably exhibiting excellent anti-fogging properties; and an acrylic block copolymer for forming same. [Solution] The present invention pertains to: an acrylic block copolymer which comprises repeating hydrophilic blocks and hydrophobic blocks, and which is characterized in that (1) the solubility parameter of a polymer that constitutes a hydrophobic block is less than 10 [cal/cm2]1/2 and the solubility parameter of a polymer that constitutes a hydrophilic block is 10 [cal/cm2]1/2 or more, and (2) the hydrophobic block is a polymer having a glass transition temperature of 50°C or lower; and an anti-fogging film containing the acrylic block copolymer.

Description

Acrylic block copolymer and antifogging film containing the same

The present invention relates to an acrylic block copolymer and an antifogging film comprising the same.

The antifogging film (fogging prevention film) is, for example, a) a window glass of a building structure, a car, etc. b) a mirror surface of a bathroom or vanity stand, c) a lens or lens cover such as glasses, goggles or face mask, d) Various types of lighting, covers for lighting, such as headlights, e) displays, covers for monitors, etc. f) fogging (diffuse reflection of light) due to condensation such as glass surfaces such as cold storage showcases or transparent resin surfaces It is used for the part / member to be obtained.

As the principle of antifogging, for example, 1) a method of modifying surface wetting, 2) a method by water absorption, 3) a method by water repellency, 4) a method by temperature control, etc. are known. Among these, the method by water absorption in the above 2) is superior to other methods in that the antifogging effect has high durability.
In the method by water absorption, by coating a hydrophilic polymer film on the substrate surface, water can be absorbed by the film surface, so that the formation of water droplets can be suppressed on the surface. As a result, a sustained antifogging effect can be exhibited.

As such water absorption type antifogging films, those using various polymer materials have been developed. For example, an article, an organic-inorganic composite antifogging film containing an organic substance and an inorganic oxide formed on the article, the organic substance containing a water-absorbent resin, the inorganic oxide containing silica, the organic substance An article with an antifogging film is known in which the inorganic composite antifogging film contains the water-absorbent resin as a main component, and the organic-inorganic composite antifogging film further contains an ultraviolet light absorber and / or an infrared light absorber. ).

For example, it is an antifogging article having a substrate and a water absorbing layer containing a crosslinked resin disposed on the surface of the substrate, wherein the water absorbing layer contains metal oxide fine particles in a proportion of 20 to 60% by mass. There is an antifogging article characterized by containing and having a haze value of 1% or less (Patent Document 2).

Japanese Patent Application Laid-Open No. 2016-108523 Japanese Patent Application Laid-Open No. 2014-148042

However, although the conventional antifogging film can exhibit a predetermined antifogging property as an initial performance, there is a problem that the antifogging property tends to decrease with time. In particular, while the water absorption type anti-fog film is composed of a hydrophilic component, the hydrophilic component separates from the anti-fog film to cause performance degradation. That is, when the hydrophilic component is dropped from the antifogging film, the water absorption is reduced, and it becomes difficult to maintain the antifogging property.

Accordingly, the main object of the present invention is to provide an antifogging film capable of continuously exhibiting excellent antifogging properties and an acrylic block copolymer for forming the same.

As a result of extensive research in view of the problems of the prior art, the present inventor has found that the above object can be achieved by adopting a composition having a specific composition, and has completed the present invention.

That is, the present invention relates to the following acrylic block copolymer and an antifogging film comprising the same.
1. A block copolymer comprising a repetition of a hydrophilic block and a hydrophobic block, wherein
(1) The solubility parameter of the monomer constituting the hydrophobic block is less than 10 [cal / cm ² ] ^1/2 and the solubility parameter of the monomer constituting the hydrophilic block is 10 [cal / cm ² ] ^1/2 or more And
(2) The hydrophobic block is an acrylic polymer having a glass transition temperature of 50 ° C. or less
Acrylic block copolymer characterized in that.
2. The acrylic block copolymer according to item 1, wherein the hydrophilic block is an acrylamide polymer.
3. Acrylamide-based polymers have the following general formula A:

(Wherein R, R ¹ and R ² are the same or different and each represents a hydrogen atom or an alkyl group having 5 or less carbon atoms), which is a polymer of an acrylamide-based monomer Acrylic block copolymer.
4. The acrylic block copolymer according to Item 1, wherein the ratio of the hydrophilic block and the hydrophobic block is from 20:80 to 80:20 on the basis of a total of 100 mol% of the two.
5. 5. A resin composition for forming an antifogging film, comprising the acrylic block copolymer according to any one of the items 1 to 4.
6. 6. The antifogging film-forming resin composition according to item 5, which contains an organic solvent and is liquid in nature.
7. An antifogging film comprising the acrylic block copolymer according to any one of items 1 to 4.
8. The antifogging film according to claim 7, comprising a hydrophilic portion by a hydrophilic block and a hydrophobic portion by a hydrophobic block.
9. 9. An antifogging product comprising the antifogging film according to item 7 or 8 formed on the surface of an article.

ADVANTAGE OF THE INVENTION According to this invention, the antifogging film which can exhibit the outstanding antifogging property continuously, and the acryl-type block copolymer for forming it can be provided.

In particular, since the acrylic block copolymer of the present invention contains a specific hydrophobic block and a hydrophilic block, it is preferable to use an antifogging film containing a hydrophilic portion by a hydrophilic block and a hydrophobic portion by a hydrophobic block. It can be formed. As a result, the antifogging film according to the present invention can exhibit excellent water absorption continuously. The mechanism of action is not clear, but it exerts excellent water absorption especially in the hydrophilic part, so it can rapidly absorb fine water droplets on the surface of the antifogging film, and the hydrophobic part has the function of supporting the hydrophilic part. It is considered that because it effectively suppresses or prevents the falling off from the antifogging film due to water absorption.

The acrylic block copolymer and the antifogging film of the present invention having such characteristics can be suitably used for various products which are required to have antifogging properties. For example, a) a building structure, a window glass of a car, b) a mirror surface of a bathroom or vanity, c) a lens or lens cover such as glasses, goggles or face mask, d) a lighting cover such as various lights or headlights E) It can be applied to a display device, a cover such as a monitor, f) a glass surface such as a cold storage showcase or a transparent resin surface.

The measurement result (The magnification of 120000 times, a bright part: CHA, a dark part: DMAA) of the transmission electron microscope in Example 1 is shown.

1. Acrylic Block Copolymer The acrylic block copolymer of the present invention (the copolymer of the present invention) is a block copolymer comprising a repetition of a hydrophilic block and a hydrophobic block,
(1) The solubility parameter of the monomer constituting the hydrophobic block is less than 10 [cal / cm ² ] ^1/2 and the solubility parameter of the monomer constituting the hydrophilic block is 10 [cal / cm ² ] ^1/2 or more And
(2) The hydrophobic block is an acrylic polymer having a glass transition temperature of 50 ° C. or less
It is characterized by

In the present invention, unless otherwise specified, acrylate or methacrylate is generically referred to as "(meth) acrylate", and acrylic acid or methacrylic acid is generically referred to as "(meth) acrylic acid", unless otherwise specified.

The monomer constituting the hydrophobic block (polymer) has a solubility parameter (hereinafter also referred to as “SP value”) of less than 10 [cal / cm ² ] ^1/2 , preferably 9.8 [cal / cm ² ]. ^{It is 1/2} or less, more preferably 9.5 [cal / cm ² ] ^1/2 or less. Although the lower limit value of the SP value is not limited, it is usually about 7 [cal / cm ² ] ^1/2 .

The SP value in the present invention may be either a literature value or an actual measurement value, but it is desirable to adopt an actual measurement value when the two are significantly different. The actual values can be measured according to known methods. For example, a sample (usually a polymer) is prepared by using 20 kinds of solvents (acetone, methylcyclohexane, methyl ethyl ketone, tetrahydrofuran, metaxylene hexafluoride, HFE-7100 (hydrofluoroether), dimethyl sulfoxide, diethylene glycol, N-methylpyrrolidone, acetonitrile, Conduct a solubility test to determine if it is soluble in 2-propanol, 2- (2-ethoxyethoxy) ethanol, toluene, diiodomethane, acetophenone, benzaldehyde, acetic acid, 2-ethylhexanol, propylene carbonate, ethanol) Construct SP spheres (Hansen's spheres) from the SP values of the solvent that could be dissolved, and calculate the SP values of Hansen (by unit conversion if necessary) based thereon It can be. The SP value of the monomer constituting the polymer can be determined by commercially available calculation software.

As such a polymer, preferably an acrylic polymer (with the exception of the acrylamide polymer) can be exemplified. Thus, for example, methyl (meth) acrylate, ethyl (meth) acrylate, propyl (meth) acrylate, isopropyl (meth) acrylate, butyl (meth) acrylate, tert-butyl (meth) acrylate, normal hexyl (meth) acrylate, cyclohexyl ( Acrylic polymers (especially homopolymers) having monomers such as meta) acrylate, benzyl (meth) acrylate, phenyl (meth) acrylate and the like can be suitably used. That is, in the present invention, it is desirable that the hydrophobic block be composed of one kind of monomer selected from these monomers.

The acrylic polymer as the hydrophobic block preferably has a glass transition point (Tg) of 50 ° C. or less, more preferably 30 ° C. or less, and most preferably 20 ° C. or less. preferable. Thereby, higher water absorption can be obtained. The lower limit value of the glass transition point is not particularly limited, but in general, it may be about −70 ° C. (particularly about −65 ° C.). In the present invention, "an acrylic polymer as a hydrophobic block" refers to the homopolymer when it is assumed that a homopolymer is formed by the monomers constituting the hydrophobic block. Therefore, the glass transition point in the present invention refers to the glass transition point (literature value) of the homopolymer. Therefore, for example, when the hydrophobic block is composed of cyclohexyl acrylate as a monomer unit, the glass transition point of the hydrophobic block is 15 ° C., which is the glass transition point of the homopolymer of cyclohexyl acrylate. In addition, generally, the glass transition point of a homopolymer is described as the glass transition point of the monomer which comprises it.

The monomer constituting the hydrophilic block (polymer) has a solubility parameter of 10 [cal / cm ² ] ^1/2 or more, preferably 10.2 [cal / cm ² ] ^1/2 or more, more preferably 10.4 [cal / cm ² ] ^1/2 or more. Although the upper limit value of the SP value is not limited, it may be normally about 13 [cal / cm ² ] ^1/2 .

As such a polymer, an acrylamide type polymer can be used suitably, for example. Therefore, for example, the following general formula A:

(However, R, R ¹ and R ² are the same or different and each represents a hydrogen atom or an alkyl group having 5 or less carbon atoms.) A polymer of an acrylamide-based monomer can be suitably used.

Among these, monomers in which R, R ¹ and R ² are the same or different from each other and are a hydrogen atom or an alkyl group having 2 or less carbon atoms are preferable. In particular, monomers in which R is a hydrogen atom or a methyl group, and R ¹ and R ² are the same as each other and are a methyl group or an ethyl group are more preferable. Therefore, for example, N, N-dimethyl acrylamide or N, N-diethyl acrylamide can be suitably used as a monomer constituting the polymer of the hydrophilic block. Also in the hydrophilic block, it is desirable to be composed of one kind of monomer selected from these monomers.

The ratio of the hydrophobic block to the hydrophilic block can be appropriately set according to the desired antifogging property and the like. For example, it is desirable to set the ratio of the monomer constituting the hydrophobic block to the monomer constituting the hydrophilic block to be 20:80 to 80:20 based on the total 100 mol% of the both, and further 40:60. It is more desirable to set so as to be ~ 60: 40. As a result, in the block copolymer of the present invention, as a result of being able to arrange the hydrophilic part by the hydrophilic block and the hydrophobic part by the hydrophobic block relatively uniformly, it is possible to more reliably maintain the better antifogging property Become.

Moreover, in the block copolymerization of this invention, functions, such as thermosetting and photocuring, can be provided by providing a reactive group, for example. As a reactive group, a hydroxyl group, a carboxyl group, an amino group, a formyl group, a carbonyl group, an epoxy group, an isocyanate group etc. are mentioned, for example. This can be produced by using a monomer having a reactive group as a raw material.

The reactive group may be introduced as a monomer constituting the hydrophobic block, or may be introduced as a monomer constituting the hydrophilic block. In this case, it is desirable that the hydrophobic block or the hydrophilic block be composed of a homopolymer having one type of monomer having a reactive group as a monomer unit.

However, when a reactive group is introduced as a monomer constituting the hydrophobic block, the SP value of the monomer is less than 10 [cal / cm ² ] ^1/2 , preferably 9.8 [cal / cm ² ]. ^{It is 1/2} or less, more preferably 9.5 [cal / cm ² ] ^1/2 or less. Although the lower limit value of the SP value is not limited, it is usually about 7 [cal / cm ² ] ^1/2 .

On the other hand, when a reactive group is introduced as a monomer constituting the hydrophilic block, the SP value of the monomer is 10 [cal / cm ² ] ^1/2 or more, preferably 10.2 [cal / cm ² ]. ^{It is 1⁄2} or more, more preferably 10.4 [cal / cm ² ] ^1⁄2 or more. Although the upper limit value of the SP value is not limited, it is usually about 13 [cal / cm ² ] ^1/2 .

The property (form) of the block copolymer of the present invention is not limited, but in general, it is preferably in the form of liquid (in particular, a solution in which the block copolymer is dissolved). Therefore, in this case, an organic solvent may be used. Examples of the organic solvent include ester solvents such as ethyl acetate, butyl acetate, methoxybutyl acetate and methoxypropyl acetate; ketone solvents such as acetone, methyl ethyl ketone, methyl isobutyl ketone and cyclohexanone; diethyl ether, dibutyl ether, tetrahydrofuran, propylene glycol Various organic solvents such as ether solvents such as monomethyl ether acetate and diethylene glycol dimethyl ether, aromatic solvents such as toluene and xylene, and alcohol solvents such as methanol, ethanol and isopropyl alcohol can be used. In the present invention, in particular, an organic solvent capable of dissolving the block copolymer of the present invention (for example, at least one of a ketone solvent and an ester solvent) can be suitably used.

When an organic solvent is used, the amount of the organic solvent used is not limited. For example, the type of block copolymer to be used and the desired solid content in the range of 1 to 60% by weight (particularly 5 to 40% by weight) It may be set appropriately according to the viscosity of the

2. Method for Producing Acrylic Block Copolymer The method for producing an acrylic block copolymer of the present invention is, for example, (1) a first step of preparing a first polymer constituting a hydrophobic block or a hydrophilic block, (2) A second step of obtaining an acrylic block copolymer composed of the first polymer and the second polymer while preparing the second polymer constituting the hydrophilic block or the hydrophobic block in the presence of the first polymer; It can manufacture by the method of including.

In the present invention, as described above, any of a) a method of forming a hydrophilic block after forming a hydrophobic block, b) a method of forming a hydrophobic block after forming a hydrophilic block, and the like are included. In the following, the method a) is described as a representative example, but the method b) is also performed according to the method a) (the order of the first step and the second step is reversed). be able to.

First Step In the first step, the first polymer constituting the hydrophobic block is prepared. When preparing the 1st polymer which comprises a hydrophobic block, it is preferable to prepare an acryl-type polymer as a 1st polymer as shown above. Therefore, as monomers (raw materials), for example, methyl (meth) acrylate, ethyl (meth) acrylate, propyl (meth) acrylate, isopropyl (meth) acrylate, butyl (meth) acrylate, tert-butyl (meth) acrylate, normal hexyl ( Meta) acrylate, cyclohexyl (meth) acrylate, benzyl (meth) acrylate, phenyl (meth) acrylate etc. can be used suitably.

Moreover, the monomer which has a reactive group can also be used as a monomer. For example, a monomer having one or more hydroxyl groups as a reactive group can be suitably used. For example, 2-hydroxyethyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, 2-hydroxybutyl (meth) acrylate, 2-hydroxy-3-phenoxypropyl (meth) acrylate, 2- (meth) acryloyloxyethyl -2-hydroxypropyl phthalate, glycerol mono (meth) acrylate and the like. A monomer having a hydroxyl group can crosslink the block copolymer by using a crosslinking agent such as an isocyanate compound in combination, and as a result, it is possible to provide an antifogging film having higher film strength. Monomers having other reactive groups can also be used appropriately as long as the effects of the present invention are not impaired.

However, the monomer having a reactive group is also required to satisfy a predetermined SP value. For example, in the case of preparing the first polymer constituting the hydrophobic block, the monomer having a reactive group may also be selected to have an SP value of less than 10 [cal / cm ² ] ^1/2 . In addition, when preparing the first polymer constituting the hydrophilic block, as the monomer having the reactive group, one having an SP value of 10 [cal / cm ² ] ^1/2 or more may be selected.

When using said crosslinking agent, the kind of crosslinking agent is not specifically limited, When using what has a hydroxyl group as said monomer, an isocyanate type compound can be used suitably. More specifically, for example, 2-isocyanatoethyl methacrylate, 2-isocyanatoethyl acrylate, 1,1- (bisacryloyloxymethyl) ethyl isocyanate and the like can be mentioned. A commercial item can also be used for these crosslinking agents.

The polymerization of the monomers is preferably carried out in the liquid phase. Accordingly, as a solvent, for example, ester solvents such as ethyl acetate, butyl acetate, methoxybutyl acetate and methoxypropyl acetate; ketone solvents such as acetone, methyl ethyl ketone, methyl isobutyl ketone and cyclohexanone; diethyl ether, dibutyl ether, tetrahydrofuran, propylene glycol Use of various organic solvents such as ether solvents such as monomethyl ether acetate and diethylene glycol dimethyl ether, aromatic solvents such as toluene and xylene, and amide solvents such as dimethylformamide (DMF), dimethylacetamide (DMAc) and diethylformamide Can.

Moreover, in the case of superposition | polymerization, well-known additives, such as a polymerization initiator (thermal polymerization initiator) and a RAFT reagent, can also be mix | blended as needed. As a thermal polymerization initiator, for example, an azo compound such as dimethyl 2,2′-azobis (2-methylpropionic acid), 2,2′-azobisbutyronitrile, a peroxide such as benzoyl peroxide, etc. are used. be able to. As the RAFT reagent, for example, 2-cyano-2-propyldodecyltrithiocarbonate can be used.

The reaction conditions in the liquid phase are not particularly limited. For example, the reaction temperature may be appropriately set within the range of about 40 to 90 ° C., and the reaction time may be within the range of about 1 to 15 hours. Thus, the first polymer can be prepared.

Second Step In the second step, an acrylic block copolymer composed of the first polymer and the second polymer is obtained while preparing the second polymer constituting the hydrophilic block in the presence of the first polymer. .

As the second polymer, it is preferable to prepare an acrylamide-based polymer as described above. Therefore, as the monomer, a monomer represented by the above general formula A can be suitably used. In particular, for example, N, N-dimethyl acrylamide or N, N-diethyl acrylamide can be suitably used as a monomer (raw material) constituting the polymer of the hydrophilic block.

In addition, as a monomer constituting a hydrophilic block, a monomer having a reactive group (particularly, an acrylamide monomer) can be appropriately used within the range not to impair the effect of the present invention, similarly to the monomer constituting a hydrophobic block. .

The polymerization of the monomers is preferably carried out in the liquid phase. Therefore, the solvent is not particularly limited. For example, ester solvents such as ethyl acetate, butyl acetate, methoxybutyl acetate and methoxypropyl acetate; ketone solvents such as acetone, methyl ethyl ketone, methyl isobutyl ketone and cyclohexanone; diethyl ether, dibutyl ether Ether solvents such as tetrahydrofuran, propylene glycol monomethyl ether acetate and diethylene glycol dimethyl ether; aromatic solvents such as toluene and xylene; and amide solvents such as dimethylformamide (DMF), dimethylacetamide (DMAc) and diethylformamide. Organic solvents can be used.

The reaction conditions in the liquid phase are not particularly limited. For example, the reaction temperature may be appropriately set within the range of about 40 to 90 ° C., and the reaction time may be within the range of about 1 to 15 hours.

After completion of the reaction, the acrylic block copolymer as the reaction product may be recovered. The recovery method is not particularly limited. For example, (a) a step of preparing a solution by dissolving a reaction product in an organic solvent, (b) an acrylic block copolymer by mixing a poor solvent with the solution. It can be carried out by a method comprising the steps of forming a precipitate, and (c) recovering the precipitate by solid-liquid separation.

In the above (a), the solution is prepared by dissolving the reaction product in an organic solvent. The organic solvent is not limited as long as it can dissolve the acrylic block copolymer which is the reaction product. For example, alcohol solvents such as methanol, ethanol, isopropyl alcohol, 1-propanol, 1-butanol, ethyl acetate Ester solvents such as butyl acetate, methoxybutyl acetate and methoxypropyl acetate; Ketone solvents such as acetone, methyl ethyl ketone, methyl isobutyl ketone and cyclohexanone; diethyl ether, dibutyl ether, tetrahydrofuran, propylene glycol monomethyl ether acetate, diethylene glycol dimethyl ether and the like Use of various organic solvents such as ether solvents, aromatic solvents such as toluene and xylene, and hydrocarbon solvents such as normal hexane and cyclohexane It can be.

The concentration of the solution is not particularly limited, and can be appropriately set, for example, in the range of about 1 to 60% by weight (preferably 5 to 40% by weight) according to the type of reaction product and the like.

In the above (b), a precipitate of the acrylic block copolymer is formed by mixing the poor solvent in the solution.

The poor solvent may be appropriately selected according to the type of solvent (good solvent) used in the reaction. For example, when an ester solvent, a ketone solvent or the like is used as the solvent, a low polar solvent (hydrocarbon solvent, aromatic solvent or the like) or the like can be used as a poor solvent. For example, when an ether solvent or the like is used as a solvent, an alcohol solvent or the like can be used as a poor solvent.

The mixing amount of the poor solvent is not limited, and may be an amount sufficient to precipitate almost all of the acrylic block copolymer contained in the solution.

In the above (c), the precipitate is recovered by solid-liquid separation. The solid-liquid separation method is not particularly limited, and may be, for example, according to a known method such as pressure filtration or centrifugation. The obtained acrylic block copolymer may be subjected to a drying treatment and the like as necessary.

3. Antifogging Film The present invention includes an antifogging film containing an acrylic block copolymer and an antifogging product in which the antifogging film is laminated on the surface of an article.

The antifogging film of the present invention contains the acrylic block copolymer of the present invention. In particular, the acrylic block copolymer of the present invention has a function of self assembly (phase separation). Therefore, when forming a film using an acrylic block copolymer, as a result of forming a film in a phase-separated state, a self-assembled film having a hydrophilic part by a hydrophilic block and a hydrophobic part by a hydrophobic block is formed. Be done. As a result, not only excellent antifogging properties can be exhibited initially but also antifogging properties can be exhibited continuously. Therefore, as long as such effects are not hindered, other components may be contained, but usually, the acrylic block copolymer of the present invention is contained in an amount of about 95 to 100% by weight in the antifogging film (particularly 99 100% by weight) is preferably included.

The structure composed of the hydrophilic part by the hydrophilic block and the hydrophobic part by the hydrophobic block generally takes various forms depending on the volume ratio of the both, but may be any form. For example, a) a structure (spherical structure) in which spherical hydrophilic parts (or hydrophobic parts) are dispersed in a matrix consisting of hydrophobic parts (or hydrophilic parts), b) columnar hydrophilic parts (or hydrophobic parts) have hydrophobic parts A structure (cylindrical structure) dispersed in a matrix consisting of (or hydrophilic portions), a c-like structure in which plate-like hydrophilic portions and plate-like hydrophobic portions are alternately arranged (alternate lamella structure), and the like can be mentioned. These structures can be confirmed, for example, by analysis with a transmission electron microscope (TEM).

In the antifogging film of the present invention having such a structure, the hydrophobic portion is mainly composed of an acrylic polymer, and the hydrophilic portion is mainly composed of an acrylamide polymer. In the hydrophilic part, fine water droplets attached to the surface of the antifogging film can be absorbed, so that excellent antifogging properties can be exhibited. In the hydrophobic part, since it plays a role of supporting and fixing the hydrophilic part, it is possible to effectively suppress the detachment of the hydrophilic part from the antifogging film by water, and as a result, the excellent antifogging property is sustained. It becomes possible.

In particular, the antifogging film of the present invention maintains excellent antifogging properties because it is a self-assembled film (phase separation film) composed of a hydrophobic portion containing an acrylic polymer and a hydrophilic portion containing an acrylamide polymer. It becomes possible. In the random structure (homogeneous structure), the desired water absorption performance can not be obtained unless the proportion of the polymer (acrylamide type polymer) constituting the hydrophilic part is large. On the other hand, when the phase separation is performed, the acrylamide polymer is present together to a certain extent (without being uniformly and finely dispersed), so that the water absorption performance is easily exhibited even if the molar ratio is relatively small. Also in the antifogging film of the present invention, since it has a phase-separated structure, excellent water absorption can be exhibited continuously.

On the other hand, in the film of an acrylamide type polymer (homopolymer) alone, although the antifogging property of the initial stage is developed, the acrylamide type polymer is dissolved in water, so that the antifogging property can not be sustained. On the other hand, the antifogging film of the present invention has a structure in which the hydrophilic part and the hydrophobic part are phase-separated, so that the hydrophobic part plays the role of preventing the dropout of the hydrophilic part. You can expect.

The thickness of the antifogging film can be appropriately set depending on the application, desired antifogging property, etc., usually in the range of about 1 to 900 μm (particularly 5 to 500 μm), but is not limited thereto.

The method for forming the antifogging film of the present invention is not particularly limited, and for example, by a method including the step of drying after forming a coating film by a coating liquid in which the acrylic block copolymer of the present invention is dissolved in a solvent. It can be implemented.

The preparation of the coating solution can be carried out by dissolving or dispersing the acrylic block copolymer of the present invention in a suitable solvent. The solvent is not particularly limited, and examples thereof include ester solvents such as ethyl acetate, butyl acetate, methoxybutyl acetate and methoxypropyl acetate; ketone solvents such as acetone, methyl ethyl ketone, methyl isobutyl ketone and cyclohexanone; diethyl ether, dibutyl ether, Various organic solvents such as ether solvents such as tetrahydrofuran, propylene glycol monomethyl ether acetate and diethylene glycol dimethyl ether, aromatic solvents such as toluene and xylene, alcohol solvents such as methanol, ethanol, isopropyl alcohol, 1-propanol and 1-butanol A solvent can be used.

The concentration of the coating solution can be appropriately set according to the type of acrylic block copolymer to be used, the desired viscosity of the coating solution, etc., but usually about 1 to 60% by weight (preferably 5 to 40%) It should be in the range of%).

The method of forming the coating film is not particularly limited, and for example, a) after forming a coating film on a support, the antifogging film obtained by drying is separated from the support to form a single antifogging film B) a method of forming a coating film directly on the surface of the article to which antifogging properties are to be applied, and drying it.

In the method a), since the antifogging film is in an independent state alone, it can be used at any place by the user.

In the case of the coating film formation by the method of said a), peeling is facilitated by apply | coating a mold release agent beforehand to the support body surface in which the coating film was formed. Moreover, in order to protect the surface, the antifogging film after peeling can also laminate | stack a release film on both surfaces or single side.

The support is not limited, and may be, for example, glass, ceramics, metal, plastics or the like. Further, the surface shape of the support is also not limited, and may be, for example, any of a flat surface, a curved surface, and an uneven surface (rough surface).

When the antifogging film is applied to the surface of the article, it may be attached using an adhesive or a pressure-sensitive adhesive, if necessary.

In the method b), the antifogging film can be directly applied to the article, so that the manufacturing process can be simplified.

The article targeted by the method of the above b) is not particularly limited, and can be applied to any article for which antifogging properties are required.

In the method b), the surface of the article may be treated with an appropriate adhesive or pressure-sensitive adhesive, or a primer, in order to enhance the adhesion between the article surface and the antifogging film.

As described above, when a coating film is formed on the surface of a support or an article, the coating method is not limited, and various coating methods such as brush, roller, spray, blade, dipping and the like can be adopted.

Subsequently, an antifogging film can be obtained by drying the coating film (undried coating film) formed by methods, such as said a) and b). In this case, drying may be either heat drying or natural drying, but in particular, it is preferable to relatively slowly dry at around room temperature (especially 5 to 35 ° C.). Thereby, sufficient time for an acrylic block copolymer to self-organize (phase separation) can be ensured. As a result, it is possible to obtain an antifogging film having the above-mentioned spherical structure, cylindrical structure, alternate lamella structure and the like. In addition, since the heat treatment such as thermal annealing is unnecessary in the formation of the antifogging film, it can also contribute to the simplification of the manufacturing apparatus and the like.

As an antifogging product which formed such an antifogging film on the article surface, it is the same as that of the conventional antifogging product, for example, a) window glass of a building structure, a car, etc. b) mirror surface of bathroom and vanity C) Lenses or lens covers such as glasses, goggles and face masks d) various illuminations, lighting covers such as headlights d) covers such as display devices and monitors e) glass surfaces such as a cold storage showcase or the like A transparent resin surface etc. are mentioned.

Examples and comparative examples are shown below, and the features of the present invention are more specifically described. However, the scope of the present invention is not limited to the examples.

In addition, the symbol (in Table 1) in an Example shows the following compounds (monomer), respectively.
CHA: cyclohexyl acrylate (cyclohexyl acrylate)
DMMA: N, N-dimethyl acrylamide HeA: normal hexyl acrylate (hexyl acrylate)
HeMA: normal hexyl methacrylate (methyl methacrylate)
BnA: benzyl acrylate (benzyl acrylate)
BuMA: normal butyl methacrylate (butyl methacrylate),
MMA: methyl methacrylate (methyl methacrylate),
IBXA: Isoboronyl Acrylate FA-513AS: Dicyclopentanyl Acrylate

Example 1
(1) Synthesis of block copolymer In a two-necked flask, cyclohexyl acrylate (CHA) (7.71 g, 50 mmol,) as the first component monomer, 2-cyano-2-propyldodecyl trithiocarbonate (0.35 g, as the RAFT reagent) 1.00 mmol), dimethyl-2,2'-azobis (2-methylpropionic acid) (0.12 g, 0.50 mmol) as a polymerization initiator, ethyl acetate (7.71 g) as a solvent, and nitrogen bubbling the reaction mixture The mixture was stirred for 30 minutes while stirring. The reaction mixture was warmed to 80 ° C. and stirred at 80 ° C. for 2 hours. The reaction conversion was confirmed to be 90% or more by 1 H-NMR. Thereafter, N, N-dimethyl acrylamide (DMAA) (4.95 g, 50 mmol) as a second component monomer, and dimethyl 2,2'-azobis (2-methylpropionate) (0.12 g, 0.50 mmol) as a polymerization initiator ), Ethyl acetate (4.95 g) was added as a solvent, and the reaction mixture was stirred at 80 ° C. for 2 hours. After completion of the stirring, the reaction mixture was diluted with ethyl acetate and added dropwise to a poor solvent, normal hexane, to carry out a reprecipitation operation. The white solid obtained was dried under reduced pressure to obtain a target block copolymer (CHA / DMAA = 50/50 molar ratio).
(2) Preparation of block copolymer self-assembled film The block copolymer obtained in the above (1) was dissolved in ethyl acetate to prepare a solution with a concentration of 5% by weight. The obtained solution was poured into a petri dish coated with a release agent so that the liquid height became 1 cm. By drying at room temperature for 24 hours, a block copolymer self-assembled film (film thickness: about 500 μm) was produced as a copolymer film.
(3) Structural Analysis of Self-Assembled Film The structure of the self-assembled film obtained in (2) above was analyzed with a transmission electron microscope (TEM) (120,000 ×). The results are shown in FIG. As shown in FIG. 1, it was confirmed that the alternate lamella structure in which the hydrophobic portions (light portions) made of CHA and the hydrophilic portions (dark portions) made of DMAA were alternately arranged in a stripe pattern.

Example 2
A block copolymer (CHA / DMAA = molar ratio 25/75) was prepared in the same manner as in Example 1 except that CHA / DMAA = molar ratio 25/75, and then it was used in the same manner as in Example 1. The copolymer film was prepared.

Example 3
A block copolymer (CHA / DMAA = 75/25 molar ratio) was prepared in the same manner as in Example 1 except that the CHA / DMAA = 75/25 molar ratio was changed, and then used in the same manner as in Example 1. The copolymer film was prepared.

Example 4
A block copolymer (HeA / DMAA = 50/50 molar ratio) was prepared in the same manner as in Example 1 except that normal hexyl acrylate (HeA) was used instead of CHA, and then it was used in the same manner as in Example 1. The copolymer film was prepared.

Example 5
A block copolymer (HeMA / DMAA = 50/50 molar ratio) was prepared in the same manner as in Example 1 except that normal hexyl methacrylate (HeMA) was used instead of CHA, and then it was used in the same manner as in Example 1. The copolymer film was prepared.

Example 6
A block copolymer (BnA / DMAA = 50/50 molar ratio) was prepared in the same manner as in Example 1 except that benzyl acrylate (BnA) was used instead of CHA, and then it was used in the same manner as in Example 1. The copolymer film was prepared.

Example 7
A block copolymer (BuMA / DMAA = 50/50 molar ratio) was prepared in the same manner as in Example 1 except that normal butyl methacrylate (BuMA) was used instead of CHA, and then it was used in the same manner as in Example 1. The copolymer film was prepared.

Comparative Example 1
A block copolymer (MMA / DMAA = 50/50 molar ratio) was prepared in the same manner as in Example 1 except that methyl methacrylate (MMA) was used instead of CHA, and then it was used in the same manner as in Example 1. The copolymer film was prepared.

Comparative example 2
A block copolymer (IBXA / DMAA = 50/50 molar ratio) is prepared in the same manner as in Example 1 except that isoboronyl acrylate (IBXA) is used in place of CHA, and then it is used with Example 1 and A copolymer film was produced in the same manner.

Comparative example 3
A block copolymer (FA-513AS / DMAA = 50/50 molar ratio) was prepared in the same manner as in Example 1 except that dicyclopentanyl acrylate (FA-513AS) was used instead of CHA, and then used. In the same manner as in Example 1, a copolymer film was produced.

Comparative example 4
A random copolymer (CHA / DMAA = 50/50 molar ratio) was prepared by the same procedure as in Example 1 except that CHA and DMMA were simultaneously blended, and then used to prepare a copolymer in the same manner as in Example 1. A coalesced membrane was made.

Test Example 1
The antifogging properties of the copolymer films obtained in the examples and comparative examples were evaluated. The method for evaluating the antifogging property is as follows. The antifogging coating test piece is disposed at a position 1 cm high from the water surface of the 40 ° C. warm water bath in the air (room temperature 20 ° C.) so that the copolymer film faces downward. The copolymer film was exposed to steam from a hot water bath.
After 2 minutes, it was visually confirmed whether or not haze was formed on the copolymer film. As a result, the case where cloudiness does not occur on the copolymer film surface is described as "o", and the case where cloudiness occurs on the copolymer film surface is described as "x". The results are shown in Table 1.

In addition, SP value (unit: [cal / cm < ² >] < ^1/2 >) of the polymer which comprises each block is as follows.
CHA: 8.8
HeA: 8.2
HeMA: 8.3
BnA: 9.5
BuMA: 8.5
MMA: 8.8
IBXA: 8.3
FA-513AS: 8.6
DMAA: 10.5

As is clear from the results of Table 1, it is understood that the block copolymer film consisting of CHA and DMAA in Examples 1 to 3 can obtain excellent antifogging properties. In particular, as apparent from FIG. 1, it can be seen that, with the antifogging film of the present invention, a film capable of microphase separation (self-assembly) can be prepared, and high antifogging durability can be expected. It was confirmed that the copolymer films of Examples 4 to 7 exhibited good antifogging properties other than the combination of CHA and DMAA. In particular, in the case of having a low glass transition point (Tg), as a result of being able to reliably form a film undergoing microphase separation (self-organization), it is understood that it contributes to the development of good antifogging properties. This is considered to be due to having a low Tg (around room temperature) to be in a non-glass state at an antifogging test temperature (around room temperature) and to be in a state where it is easy to absorb water vapor.

On the other hand, it can be seen that the copolymer films of Comparative Examples 1 to 3 are block copolymer films using components having a high Tg other than CHA, so that the desired antifogging properties can not be obtained. This is considered to be because the high Tg causes the hydrophobicity and the crystallinity to be increased, and as a result, the water absorption is inhibited, so that the antifogging property is lowered.

Further, as apparent from the results of Comparative Example 4, it is understood that even if the combination of CHA and DMAA is used, the desired antifogging property can not be obtained in the random structure. The random structure does not form a self-assembled film having a microphase separation structure. In order to obtain antifogging properties, it is considered that a block structure is necessary for the preparation of a self-assembled film having a microphase separation structure.

According to the present invention, since a block copolymer film having a microphase separation structure can be produced, good antifogging properties can be obtained, and as a result, it can be used as an antifogging film applied to various articles.

Claims

A block copolymer comprising a repetition of a hydrophilic block and a hydrophobic block, wherein
(1) The solubility parameter of the monomer constituting the hydrophobic block is less than 10 [cal / cm 2 ] 1/2 and the solubility parameter of the monomer constituting the hydrophilic block is 10 [cal / cm 2 ] 1/2 or more And
(2) The hydrophobic block is an acrylic polymer having a glass transition temperature of 50 ° C. or less
Acrylic block copolymer characterized in that.
The acrylic block copolymer according to claim 1, wherein the hydrophilic block is an acrylamide polymer.
Acrylamide-based polymers have the following general formula A:

(Wherein R, R 1 and R 2 are the same or different and each represents a hydrogen atom or an alkyl group having 5 or less carbon atoms), which is a polymer of an acrylamide-based monomer Acrylic block copolymer.
The acrylic block copolymer according to claim 1, wherein the ratio of the hydrophilic block and the hydrophobic block is 20:80 to 80:20 based on a total of 100 mol% of the two.
A resin composition for forming an antifogging film comprising the acrylic block copolymer according to any one of claims 1 to 4.
The resin composition for anti-fogging film formation of Claim 5 which contains an organic solvent and whose property is liquid.
An antifogging film comprising the acrylic block copolymer according to any one of claims 1 to 4.
The antifogging film according to claim 7, comprising a hydrophilic portion by a hydrophilic block and a hydrophobic portion by a hydrophobic block.
An antifogging product comprising the antifogging film according to claim 7 or 8 formed on the surface of an article.